Variations in the Thermal Pattern along the Campbell Glacier Axis (Terra Nova Bay, Antarctica)

M. Motta, M. Pavan & C. Smiraglia

¹Dipartimento di Scienze della Terra, Università di Torino, Via Valperga Caluso 35, 10125 Torino - Italy
²Dipartimento di Informatica e Scienze dell’Informazione, Università di Genova,Viale Dodecaneso 35, 16146 Genova - Italy
³Dipartimento di Scienze della Terra, Università di Milano, Via Mangiagalli 34, 20133 Milano  - Italy

Received 22 June 2001; accepted in revised form 19 February 2002
 

Abstract - This paper presents the preliminary results of a study of the changes in the glacial thermal pattern at a depth of 0-12 m, measured from the tongue to the head of Campbell Glacier by means of 32 thermal profiles in trenches down to 2.2 m and temperatures measured in coring holes. A steady drop in the below-surface temperature according to a gradient similar to that of the air was observed in relation to the altitude of the site, whereas at lower depths the gradient decreased, dropping down to zero at 12 metres. Measurements taken at different times of the day revealed marked fluctuations in the first metre. These diminished to a great extent in the next 1.2 metres until totally disappearing. The thermal gradient was almost always very high and more than sufficient to sustain constructive metamorphism, as shown by the stratigraphic analyses. Variations in this gradient along the axis of the glacier led to the identification of two thermal patterns. In the lower coastal sites, the shallow layers release a heat flux to the deeper layers for the entire profile, whereas the maximum below-surface temperature of the other sites was comparable to that reported by Liston et al. (1999) in Dronning Maud Land and is attributed to a maximum absorption of solar radiation at a depth of several centimetres. The below-surface maxima of Campbell Glacier are higher (as high as 5.4° compared to 3-4°C), but closer to the surface (about 1 cm in depth). The differences between the two patterns are also apparent in the temperature of the air near the ground: the sites with the below-surface maximum always have colder air in contact with the ground and generally a slight rise at 0.5 - 1 m, followed by another drop. The thermal profiles of the air at the coastal sites are rather irregular, 3-4°C warmer than the snow at a depth of 1 cm.  The maximum snow cover temperature thus matches the ground surface temperature in these profiles.
 

*Corresponding author (mmotta@mail.unito.it)